Arctic White 91 RS

In some ways the LO3 never ceases to amaze me...

Case in point last weekend, I went on a road trip. The car has orignal engine and tranny, no work on either 234,5xx miles on it. On the trip there the RS averaged exactly 32 mpg my speed on the highway was 65-70 mph on average. This beat the cars prior best of 31.5 mpg by .5 mpg. Car had been lined up recently and I thinked this helped eek out the extra .5 mpg.

My LS1 T/A is a M6 and is very hard pressed to get the same mpg. The LS1 cars best is 32.8 mpg

NJ SPEEDER

41 fewer cubes and 6 fewer injectors
really what helps it the most si that it is a low pressure system. at around 10 psi through 2 injectors it is way easier to be efficiant than at the 45psi( i think thats it) through 8 injectors that LS1's run stock.
my best was also 32, my trick was that i did it 3 tanks in a row. from trenton, nj to norwich, ny to elmira, ny and back to trenton,nj. got about 1200 miles out of 3 fill ups hehe


later
tim

My305camaro

I got ya beat!!

When I go to the track, the guy I go with always drives his Jeep there. On the way back I ride his butt and draft him all the way home (about 1 1/2 hrs.) I can easily knock down 33 mpg with the new cam and high FP. You would be amazed at how much wind does at 75-80 mph. The box-on-wheels (other wise known as a jeep) cuts a huge hole in the wind that the old RS can sit in...and I barely hear the first bit of wind noise.

alohamike

So why's my POS '92 only getting 19-20 mostly highway miles per gallon? Mostly stock with a jet chip, cat-back and the truck air-lid (which seems to have decreased the mileage!?)

brharris27370

Jet chip richens the fuel mixture up TOO much. I custom burned my chip and with 3.42 gears I can still get 26 mpg which is the same as my 3.23 geared 99 TA LS1 A4. I got 29 and 30 on the 2.73 gears.

92blue

iTrader: (1)

What the hell? I got 21 mpg on highway when my car was bone stock. Not that its far from stock now, but still.

Slade1

With my 2.73's I got a max of 38 mpg during a trip to California with a full load of stuff in the car.

With my 3.23's I get only 28 mpg, but still pretty decent.

Yeah these LO3's are surprising engines...

brodyscamaro

not calling BS but that is hard to believe

Slade1

Not kidding, even I was amazed at the mileage I was getting. 12 gallon fillups every 400-430 miles... like I said it was only a max.. the avg came down to like 33 mpg. At the time I did a full tuneup and had alignment done with my 15x7 rims.

It was just straight highway large stretches at a time would wait till it dipped into red so less than a gallon left in tank then first station spotted got gas. I dunno which particular fuel did it in which state, but mind you this was during December when temps were fairly cool along the I-40, so always getting a cold charge of air for engine... Key memories of this trip.. snow in Texas lol...

come to think of it that 38 came with a lot of help from good ol gravity... I think it was in New Mexico just before Albequerque lotsa downhill action...

FLYNLOW92rs

iTrader: (53)

I got 29.7 mpg..........and look at my wing........

I haven't tested it without the wing.......but i'm sure it could do just over 30 mpg

alohamike

Even before the jet chip I wasn't getting better than 21. It was about 23 before I put in the 3:23 lim-slip. Too rich sounds right though the plugs are clean but the tailpipe is blacker than I would expect from a properly tuned car running unleaded. Time to rebuild the TBI?
How about a poll?! I'm with brodyscamaro. It's pretty hard to believe a v-8 getting mileage that high. Those are rice-burner numbers!

SC2camaro

hey guys

new to the board

But in reference on Tbi getting gas mileage. my 1988 sc2 coupe gets 29-30 when i went to bristol TN. Also another thing that hurts gas mileage is ( gas mileage is directly related to the attitude of the right foot ) but in respect i didn't believe the gas mileage also but i checked it to and there. Also some cars got the HIGHWAY mode patch in the chip mine does. what that means is after 52 mph with a low load value(lv8) the computer leans the system down. the computer also looks at TPS #'s to. and once the computer gets the info and the throttle has not changed in 20-25 seconds highway mode is active until the load value goes up. i have a air fuel gauge hooked up when 16.1 is the last led to light up when the car is in highway mode it will not light up any lights. it also works with cruise but it takes longer for it to respond with cruise but it does work even with the ac on
thats how they can get gas mileage and @ 70 mph turning 2k rpm's helps too!

Slade1

Yeah, that's around what I ran most of the time, 2k rpm to 2500 rpm... The right foot attitude really changes that. Yeah, something you notice the car will run in some mode where all of the sudden I get amazing fuel mileage. It's pretty dramatic. I stay in city and get city 16mpg then I do all highway and get 26mpg almost instantly. (3.23s now mind you)

I think it has something to do with the VSS delete option or something for our cars, if you had some special Speedometer Key Delete option or something, basically you aren't hooked (the ecm) to a VSS sensor which is why I guess I've never experienced that 115 mph barrier that some ppl complain about. Its a strange rpo code that I just couldn't give an explanation for. I was able to push 140mph before (waaayyy off the 115 mark of my speedo) which is roughly 3700 rpm, 4th gear 2.73 gears. Now I'm pushing still 130 mph, 4000rpm, 4th, 3.23 gears so I know for sure the VSS doesn't exist in my car.

Even in the tech articles, there is a mod to disconnect the VSS that limits some cars, which ends up causing a code 23. The vehicle speed sensor is also what does that 115 mph limit issue.

Just for curiosity's sake, how many of you have this delete option and if so, can or can't go past 115 based off the speedometer? The code is E9Z. Speedometer Key (Delete)

SC2camaro

hey guy

my car has the E9Z option, but it waill not kill out @115. But there is a vss on our cars. it has to be for the cruise control to work. Also if you have a laptop with Win ALDL on it turn it on and drive the car the puter does see MPH i guess the VSS is in the back of the speedo.

I know on the buick GN's it is in the back of the speedo housing
never tore the camaro guages down.

Slade1

Forgot to mention, I don't got cruise control. Those with cruise control will have a VSS, but not necessarily a 115 mph lock... hence the need for a e9z option I think...

F88,Lo3

i had 3:08-1 gears stock and i got 350 kilometers per tank and i swapped them for 3:42-1 gears andnow i have gotten 400+ kilometers per tank, i dunno why mabe its burning at a more efficient RPM or it is workin less hard to get up to speed but i am not complaning.
Chris.

azvolfan

I got 28 mpg when I picked up my '92 RS about 20 months ago and drove it out to Phoenix. And that was at about 80 mph with the cruise control on almost the whole way.

Around town I get anywhere from 22-24 mpg. No complaints about the mileage from me!!!

brodyscamaro

your foot must be as light as a feather

Slade1

With cruise control and the highway, who needs a light foot lol?

Anyways, mileage is still almost 90% dependant on the driver. You can have one of the most efficient 2 bangers around, but if you rev it like a maniac. Accelerate all the time, you can burn it all quick.

I suffer from lead foot only sometimes. Whenever I see gas jack up in price, foot gets lighter and food becomes scarce for me lol.

brodyscamaro

i was talking about his 22-24 mpg in the city.

Arctic White 91 RS

A lot of truth to that I had a rental car a new 02 Nissan Sentra for a few days. It's average gas mileage was 27 mpg, not very impressive for a 4 banger. I did drive it like I stole it, but even revving the **** out of that sorry import, it didn't accelerate as fast as the RS...and it got worse mileage for all the highway driving I was doing...

dimented24x7

iTrader: (2)

thats one thing i miss about my 305... good gas milage. My 350 still manages to pull in the mid twenties, though.

vette9190

iTrader: (2)

What the heck am i doin wrong!
I only get about 13 MPG on average, but I got a best of 26 on the way home from the UP, Michigan. Still there must be something whrong with my car for that pittiful of mileage. I still have my 2.73s in there. Oh well! If I wanted good gas mileage I would have kept my Saturn(POS!)

Slade1

Ouch 13??? Time for a tuneup lol..

I checked my latest city mileage for the last week in this blistering heat/humidity and a/c running... I'm getting 18 mpg.

If the temps stabalize and humidity goes down I avg 22 city mpg. Highway pulls a good 28-30 depending if I cruise at 70 or gun an avg 85 mph... with 90 spurts (provided safe cop free zone)... so a decent 300 mile trip I can still do at the fun speeds which is pretty good hehe... I know I can push 32 mpg, but who wants to do 65 mph the whole trip in a car like this??? No wait even better... who could endure a tankfull trip at 65 mph???

TBI305Camaro

Mine speed limiter will only kick in if im using the cruise control. I found that out one night messing around I stuckl the cruise on about 90 and kept bumping it up. at 110 it stopped and when back down. But without the cruise it will peg to the trip meter no problem

Macgyver

Best of 32 on the highway. I average about 26 MPG.

In the city, I get about 8 MPG.

vette9190

iTrader: (2)

Well at least im not the only one. By the way I tuned up the car when I got it about 5 mos ago acdelco rapidfire plugs accel cap and rotor 8.8 spiral core wires. heck i got a accel 300+ on there. My 92 bird got 19MPG and I used to do 100MPH half way to work(country roads) and back (about 45 miles one way). And my 87 Camero LT before I swapped the LG4 for a 350 got 16 MPG average, after I put an accel 300+ on it, before it was only 13.
But like I said if i wanted good gas milage I would have kept My Saturn(POS).

Slade1

Take your pick... gas mileage or power... the LO3 is probably the best compromise of both... If I wanted to do all track, then I'd forego the street design and go all strip... until I'm loaded, the LO3 compromise will have to tide me over...

Arctic White 91 RS

My car has the E9Z production code.

Now exactly what does that mean? If I understood the above, it means the computer has a special low load gas saving mode that it goes into and leans the A/F out to about 16:1 crusing. It also means the car is not speed limited by the VSS?

I think a working EGR is very important to getting the A/F to lean out at 16:1 and work properly. The EGR provides a cooling effect on the cylinders and allows a leaner A/F. Some with low mpg may want to check and make sure their ERG valves aren't blocked. I replaced the EGR, few years ago and it had a solide block of carbon in it.

SC2camaro

hey guys

I took my 88 1sc camaro to bristol Va last year and with the cruise on and the air going up the mountains i got 28.2 cruise ser at 70. Also the nice thing about it that the lo3 has enuff bottom end torque that it didn't even un lock from overdrive. MY buddy has a 99 chevy s10 4 banger got just over 27 mpg and couldn't keep up with me going up the mountain


Artic, I disagree with you about the EGR helping to lean out the A/F. cause i have a A/F guage on my car and it leans out to about 16.5/1 and my EGr valve is not working. or the computer senses that it's not working, and i know i have highway mode from when i read the chip. cause it is set to go into highway mode over 52 MPH

What the E9Z is it is a speedo key delete from what the decoder says. has something to do with the speed limiter mode

the highway mode is completely different.

Also how does the computer see that the EGR is opening?
all it has a vacuum solonoid, . my solonoid works the egr passage is free and i also bought a new valve and put on it %% bucks and that didn't help so i put the old vavle back ont and took the new one back. i hate seeing that damn SES light on , and it only comes on if the car locks into highway mode only. confirming that with my A/F guage. but the A/F guage show it to being leaning down to 16.5/1 if the EGR helps do that why is the car setting a code for the EGR ?




As i drive through the valley of GT's, I shall fear no evil, for the LO3 is with me to blast past them

Arctic White 91 RS

Key part of what I said was "lean out and work properly". I should have been more careful with my wording. Let me rephrase.

The egr provides a cooling effect to the cylinders that allows the computer to lean the A/F out to 16 to 1 or so and not retard timing or ping. The lean A/F and timing curve are what help get the good MPG. While exhaust gas is hot it is much cooler than the combuston temprature, and this helps reduce a ping or knock retard at lean A/F's.

Slade1

Uh oh.. now we're into egr talk.. me, egr and code 32 go waaaaaay back... I lost my rings to them so I know full well the damage no egr can do. this is meant for daily drivers, the egr is useless on track and on or blocked won't make a difference. Here's why.

The EGR is commanded by the ecm to activate after a certain rpm number. For my car, it commands it at 1900 and disables it after 2500. It is only for use at the greates amount of torque you make. For the LO3, that's 2400 RPM. At the highest torque rpm, combustion chamber flow, air/fuel ratio essentially there you are making the best power. You are also making the most amount of heat too. At this rpm range, combustion chamber temps skyrocket to around 7000+ degrees. I based that assumption on the fact nox are produced at that temp, and without an egr, you'd better believe you'll have up more nox than normal... (1800 vs 500 on my car...) It actually can get hotter than that though. At these temps your o-rings can burn and the oil lubrication can vaporize/ignite letting the o-rings scuff up the cylinder walls... so regular cruising ends up destroying your rings in the end... with egr, already combusted gas does not ignite and basically allows temps to drop to around 5000 F avg temp in the chambers. This also has the added effect of leaning out the fuel needed since uncombusted hydrocarbons get a second chance to combust instead of wasting that energy in a catalytic converter reaction... See to everything there is a benefit... This is how we are getting those 32 mpg miracles...

Its only called when you cruise, so stay at a consistent rpm that is around max torque. Now it knows this simply because it has a pressure sensor that is part of emissions that checks if the egr is open, will allow exhaust into the intake again. That's why if you drive like a maniac, constantly gunning the rpm, you won't see a ses light flick on, but stay at 2000 consistent without egr and it comes on.

That's my speel on egr.

As for the e9z code.. it's looking like its a speed limiter delete to me essentially...

Birdman7389

I just came off about 1K of driving in my 89' T/A l03 and cruise set between 80-85 the whole way, along with a few trips into the 1XX teens!! LOL about 24-26MPG loaded down with the A/C on. I was pretty happy

Arctic White 91 RS

Slade1,

Thanks for your informative post because I learned something.

So this sounds like it's a real good idea to keep EGR function on a daily driver. This makes me wonder if driving my car for 65,000 miles with the light on intermitantly on hurt anything...wait that was back a 50,000 miles ago...must be ok after all. However, I've learned my lesson, I didn't know the temps could go quite that high, if had I would have fixed the EGR much sooner than I did.

This also makes we want to keep the EGR function on my LS1 T/A when I install the LS6 intake.

By it sounds like the stick and auto cars get maxing out around the same MPG.

Slade1

Your welcome, its my duty not to let what happen to me happen to anyone else.

As for having it on intermittently, its not that bad.. I left it for over 6 months and learned the hard way... see people who drop the egr don't usually use these cars as daily drivers, so they never have problems. So no one thinks just why they made these things. Its not just for passing emissions, its for a lot more.

As for the stick and auto getting around the same max, yep it'll happen... at cruising speed the auto has a tc lockup giving 1:1 ratio just like a stick thereby nullifying the efficiency advantage the stick has on early gear acceleration. TC lockup can also be forced thereby making the only advantage really being the first gear since the pressure in the tranny isn't strong enough in first for lockup operation.

Jokerman

wow 28-32mpg on the high way and i was happy to be getting a solid 25mpg on my 430mile trip home with my 305 RS. Still pretty decent gas mileage for the cars i have owned (one that would get about 20mpg and the other, a 4cyl about 25mpg).

Arctic White 91 RS

Jokerman,

Before the RS I had an 86 Sport Coupe w/2.8 v6, 700R4 & 3.42 rear, that car would average 23-24mpg for most of my driving or about 1mpg less than the LO3 does in the RS. On road trips I think the best for the Sport Coupe was in the low 30's maybe but it's been so long ago I can't remember. I do know my wifes Grand Am usually gets about 34-37mpg on long trips normal driving she gets around 27-28 mpg and it's a 4 banger w/auto. I don't think the smaller engines are worth it for only a few miles a gallon overall. A friend has a Corolla, it can get 43mpg but it far less comfortable than a 3rd Gen, rides worse too and far noiser with that nasty sounds 4-cylinder weed eater pulling over 3 grand at highway speeds. My mom has 2000 Lexus (nice rice)and averages about what the RS does for normal driving and maybe 32-35mpg on the highway but I expected the Japanese to do better with technology thats 10 years newer...

SC2camaro

hey slade.

When i bought my car over a year ago i was told about the EGR system being down.But i really don't undertand how that can kill the ring in a way because motor in the 60's-early 70's didn't have egr's on them.I never heard of that killing the rings. but anyhow can you tell me how to correct my problem with mine?

i have checked the solonid and it functions correctly and i have vacuum on the hose to it. I thought it was the valve, so i replaced it it didn't help the only thing the new valve done was make the car idle real low and no power, but still got the code. so i put the old one back on it and sent the new one back. Also i checked to make sure there was not any blockages in the passages. Also how does the computer know when the valve is open? By oxygen sensor readings? cause i can get 28-29 miles to the gallons with it like that and the A/F gauge shows it to be leaning down to about 16.5/1 ratio. i would like to correct this problem so i don't kill my motor. If that can kill it. but i hate seeing htat damn orange light @ night. But i have been driving it like that for over a year now. lol it has 145k on it don't leak or burn a drop of oil. i'm the 2 owner of it and the motor has never been into. hell it still has the factory r12 freon in it. I done a tune up on it about 10k ago and it still had the factory plugs in it with about a 50k gap lol but it run fine until you matted it to WOT then it would die out.

But please help me sove my SES light EGR code i have checked everything and it show to be working but i still get the light WHY

Arctic White 91 RS

SC2,

Have you pulled the EGR off the car and made sure it's not blocked with carbon?

Slade1

First off clear your ecm by disconnecting your battery for a few mins. When you pull codes, you should only have a code 12 which repeats over and over which is ok. Next drive it around and if it comes on, check what code(s) its giving you. If you are still pulling a 32 out, put in a new egr valve, not expensive. When I took off my first one, a lot of carbon build up was there. On top of that It weighed significantly more than the new one due to carbon build up. With it off, you can start your engine and see if exhaust gases are being expelled from the egr holes. If not, is blocked on the inside of the manifold. Hopefully its just carbon build up and a good carb cleaner should degunk it. If someone physically blocked the egr passages then you have a problem. Reason why mine failed was I daily drove my car avg 2k rpm so always egr operation and didn't get it no emissions at time too so didn't matter. First I was losing oil.. didn't know why... then wot gave me smoke, then hard loads too... the o-rings will eventually fail, first they scrape against the cylinder walls and score the walls... oil blowby occurs... it just gets worse and worse and worse ...

The egr relies on negative vacuum pressure to function I think (have to recheck this). The ecm just checks if the pressure reading is correct when it calls the function, if not, blocked or failed, it will toss a code. EGR's fail in the closed position usually.

Older engines don't suffer from the same issues as newer engines for a lot of different reasons. I would have to say the shorter stroke, larger bore would be a big thing with rings since there is less travel per stroke. Another thing is parts for the smog era got cheaper and lighter... kept looking for ways to improve efficiency... so compromises in part design plays a large part too smog era is usually smaller, more efficient use of resources... emissions control etc...

The older engines were meant to run hot, high temp parts in mind no concern that at those temps nox forms... That's why egr was introduced and o-rings got a whole lot cheaper since temps were meant to run lower...

It all fits together in the grand scheme of things, one thing leads to another etc.

Arctic White 91 RS

Slade,

Maybe you have some insight into this:

My RS is a fairly high mileage one (235,000 miles) a few times before the car started using oil and the problem was discovered and corrected.

1. oil pressure sensor had a bad O-ring and leaked when the car was running.

2. PCV valve clogged and car sucked oil into the breather

Currently the RS is using about a quart every 1,500 miles. I know the front & rear main seals leak a little, as do valve covers, but the oil loss is too much for these minor leaks. Once again the car is getting some oil in the breather but the PCV valve isn't clogged. I replaced it anyway but the oil loss remained the same. I get a puff of white smoke on start up if the car sits over night. The car does lose coolant about a quart every thousand miles or so but I know I have a coolant leak on the front of the intake manifold. Oil doesn't look like a milk shake, in fact the oil looks fairly clean after 5,000 miles. I'm currently running Mobile 1 5w-30. I check the oil at each fill up because I know the PCV can clog etc. I didn't have oil consumption to any real degree until this oil change. Some on LS1tech say the new Mobile 1 5w-30 is just barely 5w-30 and actually closer to 5w-20. I know Mobile changed the formula of Mobile on this current batch of Mobile 1 that's in the car.

Think it's the oil or the car?

Think next oil change I should try Mobile 1 10w-30 and see what happens? Car is almost due.

Thanks.

Comments appreciated.

SC2camaro

hey guys

I finally got he EGR system fixed today. Well i had already order one and put on it. i made sure that i ordered the rite one to! I crossed reference the GM part # to the GP sorenson # well i tried that one and it didn't wok. So i toke it back to work and got another valve and it didn't work. So i was like WTF. So for ****'s and giggles i look up one for a 88 5.0 truck hell it was not the same part # as for the VIN E LO3. BUt what the hell i took it and tried it and low and behold that one fixed it. I drove it about 25 miles on the bypass with the cruise on and no damn SES light.So i'm like killer. I was getting 28.2 with it think it can get better with a EGR working ?

Also while it was running today i pulled the PCV out and unhooked the vent to the breather and my motor has no blowby even @ 145k i was amazed. i would have thought there would have been a little. maybe thats due to the 10w-40 max life oil i run in it . I want to hang on to this car for a while it looks and runs great

Slade1

Well if you noticed it after using this oil, then go back to your old one. I've personally used the 5w30 mile1 synthetic and noticed no real ill effects cept in the wallet lol... losing oil at the sensor is a bad thing... its under pressure at that point still and losing it there means the engine is not getting the pressure it needs. At higher rpms much psi is needed so any loss will hurt lubrication wise...

If it was caught in time no serious damage should have occured and you should see like 15 psi idle and then spikes to red zone on high rpm runs...

If the pcv clogged then there was a significant pressure buildup which would have just shot pressure out to the breather and yeah as messy as is, is not a major deal as long as the engine never really became sealed...

coolant leaks are not uncommon, as long as its not mixing with oil its not a direct cause of oil loss...

smoke on startup means you valve seals are going... not too much to worry about... but will require replacement sooner than not...
smoke on wot means o-rings on the pistons are going.. that's a major rebuild if major scoring of the cylinder walls haven't occurred yet...

If the oil is as thin as I think they've brought it too, then yeah you may not be getting adequate lubrication at higher rpm and its vaporizing on the cylinder walls causing excessive pcv pressure but not necessarilly burning in the cylinders hence why your breather is soaked and why the pcv may clog when the oil vapor condenses back to oil on the breather... if you are losing the lubrication completely, scoring would occur and oil blowby would happen with wot causing puffs of smoke or heavy loads...

Try the oil first and see if that works... if you are getting the other problems ie wot smoke (need someone to follow you from behind when you floor the pedal) then the orings are gone going on the pistons...

using 10w30 is pretty thick stuff, should give a high pressure reading on the oil.. maxlife says it'll help seals so I guess its ok.. they sell additives for that though so you can still have the 5w30 performance...

Having the egr doesn't guarantee high mileage.. it is only commanded to run when rpm stays consistent... but yes you should see an improvement in mileage...

All this code 32 talk has my car joining in it too lol.. mine pulled a 32 few days ago... ran the engine with a cleaner to see if that will help... if not, I'll go in and wire brush the passages and test if egr isn't clogged... its its only <year old so I'm ticked at it...

Black_Widdow

iTrader: (1)

I get about 17 city and 20 highway with no SES lights. I wonder what the problem could be

91Bird305

You have no problem. Thats what these cars did stock. The only reason some of these guys are getting such great mileage is there missing catalytic converters, ignition upgrades and other small things. Some of them are a little hard to swallow. But anyways, I got 20mpg city with my deleted cat and ignition upgrade.

SC2camaro

hey Bird

I thought i would let ya know that the only mods done to my camaro is a gutted cat and a K/N filter and i can knocked down 28-29 MPG with a broke EGR. i test the car last summer when i went to bristol TN from Randleman nc i got 28.2 that was with K/N with a complete cat i just gutted the cat about 2 months ago because it was rattling. i WAS AVERAGING AROUND 70-75 MPH TOO

you don't need any upgrades for the cars to get gas mileage. Tune it up with good parts. and get a fresh O2 sensor in it. and run a good grade of fuel and it will get gas mileage


ALSO GAS MILEAGE IS DIRECTLY RELATED TO THE ATTITUDE OF THE RIGHT FOOT!

91Bird305

Deleting ur cat will increase ur gas mileage a lot. And how is that not an upgrade? Changing the things u did are upgrades that effect gas mileage.

brodyscamaro

Erics BACK!!!!!! did you ever run your car with the spray?

91Bird305

Hehehe, yeah I have...RETURNED.

Naw, never did. Ran into some big money problems and I need to sell the system. if I can't sell it, I am gonna slap it on anyways and see what happens. The system will still be for sale but I am gonna try and put it on my car anyways. I gotta find a fuel pressure saftey switch and a nitrous pressure gauge still though. But anyways, I would run with a 75 shot at first, tune it, then up to 100 and tune it. And I dare go up to a 125 shot, I am pushing my luck there. But when I have a 350 (or something) on the side ready to install, I will throw the 125 shot on there and see what happens.

Arctic White 91 RS

Long ago when my car was new and had about 10,000 miles, the RS got 29.5 mpg on long trips. The RS averaged 24-25 city driving. That was 100 percent stock down to the stock air filter. This was on cheap 87 octane gas. I bought the car new, a big part of mpg is driving style.

Good friend of mine had 88 WS6 Formula w/LO3, A4, my RS always got better mpg by 2-3 mpg. His car always seems stronger by a good margin maybe 20hp or so. I think the cars vary a little too. My RS is another of the very slow cars, even by TBI standards, but seems to be able to edge out MOST other TBI cars when it comes to MPG.

My car is still very close to stock now. The car still has the original cat, it does have a cheap-o cat back, coil, Bosche +4, 160 stat and straight wired fan now. Cruise control no longer functions. and A/C has failed.

Due to carbon I guess, the RS needs 93 octane. Wife put a tank full of 87 in a year ago after I told her not too. The mpg dropped to 19 mpg, pinged loudly etc. Can of octane booster didn't seem to help much either.

This is the same RS, I posted about being totaled and losing back in Dec 2001. I spent all my LS1 heads and cam money intended for my 99 T/A LS1 on salvaging and rebuilding the RS. The car has a new radiator and has the best alignment it's ever had.

Eric does make a fair point about some mod can help

Cat delete's are illegal and I like to breath so I'll never delete the cat from the car. However with 235,2xx miles doing a 3inch cat when I do headers, Y pipe, I pipe and add the SLP 20TL cat back seems like a good idea.